Graphic Resources?

Does anybody know of a website, free if possible, where i can find images to display/mount work in for a website. Examples of this would be empty bill boards to show a poster design in situ either on the underground or at a bus stop. Somebody holding what appears to be a flyer where i can insert my design to be held, again showing design in situ. And finally a imac so i could display work inside, maybe for websites of logo work?

Hope i have made myself clear, i am just trying to find another way of displaying work rather than displaying in a box/frame.